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    <h1 align="CENTER">Apache Server Frequently Asked
    Questions</h1>

    <p>$Revision: 1.21 $ ($Date: 2003/07/01 22:42:13 $)</p>

    <p>The latest version of this FAQ is always available from the
    main Apache web site, at &lt;<a
    href="http://httpd.apache.org/docs/misc/FAQ.html"
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    find numbers enclosed in brackets (such as "[12]"). These refer
    to the list of reference URLs to be found at the end of the
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    for the hypertext version.</p>

    <h2>The Questions</h2>

    <ol type="A">
      <!--#endif -->
      <!--#if expr="$TOC || $STANDALONE" -->

      <li value="4">
        <strong>Error Log Messages and Problems Starting
        Apache</strong> 

        <ol>
          <li><a href="#setgid">Why do I get "<samp>setgid: Invalid
          argument</samp>" at startup?</a></li>

          <li><a href="#nodelay">Why am I getting "<samp>httpd:
          could not set socket option TCP_NODELAY</samp>" in my
          error log?</a></li>

          <li><a href="#peerreset">Why am I getting
          "<samp>connection reset by peer</samp>" in my error
          log?</a></li>

          <li><a href="#wheres-the-dump">The errorlog says Apache
          dumped core, but where's the dump file?</a></li>

          <li><a href="#linux-shmget">When I run it under Linux I
          get "shmget: function not found", what should I
          do?</a></li>

          <li><a href="#nfslocking">Server hangs, or fails to
          start, and/or error log fills with "<samp>fcntl:
          F_SETLKW: No record locks available</samp>" or similar
          messages</a></li>

          <li><a href="#aixccbug">Why am I getting "<samp>Expected
          &lt;/Directory&gt; but saw &lt;/Directory&gt;</samp>"
          when I try to start Apache?</a></li>

          <li><a href="#redhat">I'm using RedHat Linux and I have
          problems with httpd dying randomly or not restarting
          properly</a></li>

          <li><a href="#stopping">I upgraded from an Apache version
          earlier than 1.2.0 and suddenly I have problems with
          Apache dying randomly or not restarting properly</a></li>

          <li><a href="#setservername">When I try to start Apache
          from a DOS window, I get a message like "<samp>Cannot
          determine host name. Use ServerName directive to set it
          manually.</samp>" What does this mean?</a></li>

          <li><a href="#ws2_32dll">When I try to start Apache for
          Windows, I get a message like "<samp>Unable To Locate
          WS2_32.DLL...</samp>". What should I do?</a></li>

          <li><a href="#WSADuplicateSocket">Apache for Windows does
          not start. Error log contains this message "<samp>[crit]
          (10045) The attempted operation is not supported for the
          type of object referenced: Parent: WSADuplicateSocket
          failed for socket ###</samp>". What does this
          mean?</a></li>

          <li><a href="#err1067">When I try to start Apache on
          Windows, I get a message like "<code>System error 1067
          has occurred. The process terminated
          unexpectedly.</code>" What does this mean?</a></li>

          <li><a href="#suseFDN">On a SuSE Linux system, I try and 
          configure access control using basic authentication.
	  Although I follow the example exactly, authentication
	  fails, and an error message "<code>admin: not a valid
	  FDN: ....</code>" is logged.</a></li>

          <li><a href="#codered">Why do I have weird entries in my
          logs asking for <code>default.ida</code> and
          <code>cmd.exe</code>?</a></li>

          <li><a href="#restart">Why am I getting server restart
          messages periodically, when I did not restart the
          server?</a></li>

          <li><a href="#modulemagic">Why am I getting &quot;module
          <em>module-name</em> is not compatible with this version of
          Apache&quot; messages in my error log?</a></li>

        </ol>
      </li>
      <!--#endif -->
      <!--#if expr="$STANDALONE" -->
    </ol>
    <hr />

    <h2>The Answers</h2>
    <!--#endif -->
    <!--#if expr="! $TOC" -->

    <h3>D. Error Log Messages and Problems Starting Apache</h3>

    <ol>
      <li>
        <a id="setgid" name="setgid"><strong>Why do I get
        "<samp>setgid: Invalid argument</samp>" at
        startup?</strong></a> 

        <p>Your <a
        href="../mod/core.html#group"><samp>Group</samp></a>
        directive (probably in <samp>conf/httpd.conf</samp>) needs
        to name a group that actually exists in the
        <samp>/etc/group</samp> file (or your system's equivalent).
        This problem is also frequently seen when a negative number
        is used in the <code>Group</code> directive (<em>e.g.</em>,
        "<code>Group&nbsp;#-1</code>"). Using a group name -- not
        group number -- found in your system's group database
        should solve this problem in all cases.</p>
        <hr />
      </li>

      <li>
        <a id="nodelay" name="nodelay"><strong>Why am I getting
        "<samp>httpd: could not set socket option
        TCP_NODELAY</samp>" in my error log?</strong></a> 

        <p>This message almost always indicates that the client
        disconnected before Apache reached the point of calling
        <code>setsockopt()</code> for the connection. It shouldn't
        occur for more than about 1% of the requests your server
        handles, and it's advisory only in any case.</p>
        <hr />
      </li>

      <li>
        <a id="peerreset" name="peerreset"><strong>Why am I getting
        "<samp>connection reset by peer</samp>" in my error
        log?</strong></a> 

        <p>This is a normal message and nothing about which to be
        alarmed. It simply means that the client canceled the
        connection before it had been completely set up - such as
        by the end-user pressing the "Stop" button. People's
        patience being what it is, sites with response-time
        problems or slow network links may experience this more
        than high capacity ones or those with large pipes to the
        network.</p>
        <hr />
      </li>

      <li>
        <a id="wheres-the-dump" name="wheres-the-dump"><strong>The
        errorlog says Apache dumped core, but where's the dump
        file?</strong></a> 

        <p>In Apache version 1.2, the error log message about
        dumped core includes the directory where the dump file
        should be located. However, many Unixes do not allow a
        process that has called <code>setuid()</code> to dump core
        for security reasons; the typical Apache setup has the
        server started as root to bind to port 80, after which it
        changes UIDs to a non-privileged user to serve
        requests.</p>

        <p>Dealing with this is extremely operating
        system-specific, and may require rebuilding your system
        kernel. Consult your operating system documentation or
        vendor for more information about whether your system does
        this and how to bypass it. If there <em>is</em> a
        documented way of bypassing it, it is recommended that you
        bypass it only for the <samp>httpd</samp> server process if
        possible.</p>

        <p>The canonical location for Apache's core-dump files is
        the <a href="../mod/core.html#serverroot">ServerRoot</a>
        directory. As of Apache version 1.3, the location can be
        set <em>via</em> the <a
        href="../mod/core.html#coredumpdirectory"><samp>CoreDumpDirectory</samp></a>
        directive to a different directory. Make sure that this
        directory is writable by the user the server runs as (as
        opposed to the user the server is <em>started</em> as).</p>
        <hr />
      </li>

      <li>
        <a id="linux-shmget" name="linux-shmget"><strong>When I run
        it under Linux I get "shmget: function not found", what
        should I do?</strong></a> 

        <p>Your kernel has been built without SysV IPC support. You
        will have to rebuild the kernel with that support enabled
        (it's under the "General Setup" submenu). Documentation for
        kernel building is beyond the scope of this FAQ; you should
        consult the <a
        href="http://www.redhat.com/mirrors/LDP/HOWTO/Kernel-HOWTO.html">
        Kernel HOWTO</a>, or the documentation provided with your
        distribution, or a <a
        href="http://www.redhat.com/mirrors/LDP/HOWTO/META-FAQ.html">
        Linux newsgroup/mailing list</a>. As a last-resort
        workaround, you can comment out the
        <code>#define&nbsp;USE_SHMGET_SCOREBOARD</code> definition
        in the <samp>LINUX</samp> section of
        <samp>src/conf.h</samp> and rebuild the server (prior to
        1.3b4, simply removing
        <code>#define&nbsp;HAVE_SHMGET</code> would have sufficed).
        This will produce a server which is slower and less
        reliable.</p>
        <hr />
      </li>

      <li>
        <a id="nfslocking" name="nfslocking"><strong>Server hangs,
        or fails to start, and/or error log fills with
        "<samp>fcntl: F_SETLKW: No record locks available</samp>"
        or similar messages</strong></a> 

        <p>These are symptoms of a fine locking problem, which
        usually means that the server is trying to use a
        synchronization file on an NFS filesystem.</p>

        <p>Because of its parallel-operation model, the Apache Web
        server needs to provide some form of synchronization when
        accessing certain resources. One of these synchronization
        methods involves taking out locks on a file, which means
        that the filesystem whereon the lockfile resides must
        support locking. In many cases this means it <em>can't</em>
        be kept on an NFS-mounted filesystem.</p>

        <p>To cause the Web server to work around the NFS locking
        limitations, include a line such as the following in your
        server configuration files:</p>

        <dl>
          <dd><code>LockFile /var/run/apache-lock</code></dd>
        </dl>

        <p>The directory should not be generally writable
        (<em>e.g.</em>, don't use <samp>/var/tmp</samp>). See the
        <a
        href="../mod/core.html#lockfile"><samp>LockFile</samp></a>
        documentation for more information.</p>
        <hr />
      </li>

      <li>
        <a id="aixccbug" name="aixccbug"><strong>Why am I getting
        "<samp>Expected &lt;/Directory&gt; but saw
        &lt;/Directory&gt;</samp>" when I try to start
        Apache?</strong></a> 

        <p>This is a known problem with certain versions of the AIX
        C compiler. IBM are working on a solution, and the issue is
        being tracked by <a
        href="http://bugs.apache.org/index/full/2312">problem
        report #2312</a>.</p>
        <hr />
      </li>

      <li>
        <a id="redhat" name="redhat"><strong>I'm using RedHat Linux
        and I have problems with httpd dying randomly or not
        restarting properly</strong></a> 

        <p>RedHat Linux versions 4.x (and possibly earlier) RPMs
        contain various nasty scripts which do not stop or restart
        Apache properly. These can affect you even if you're not
        running the RedHat supplied RPMs.</p>

        <p>If you're using the default install then you're probably
        running Apache 1.1.3, which is outdated. From RedHat's ftp
        site you can pick up a more recent RPM for Apache 1.2.x.
        This will solve one of the problems.</p>

        <p>If you're using a custom built Apache rather than the
        RedHat RPMs then you should <code>rpm -e apache</code>. In
        particular you want the mildly broken
        <code>/etc/logrotate.d/apache</code> script to be removed,
        and you want the broken <code>/etc/rc.d/init.d/httpd</code>
        (or <code>httpd.init</code>) script to be removed. The
        latter is actually fixed by the apache-1.2.5 RPMs but if
        you're building your own Apache then you probably don't
        want the RedHat files.</p>

        <p>We can't stress enough how important it is for folks,
        <em>especially vendors</em> to follow the <a
        href="../stopping.html">stopping Apache directions</a>
        given in our documentation. In RedHat's defense, the broken
        scripts were necessary with Apache 1.1.x because the Linux
        support in 1.1.x was very poor, and there were various race
        conditions on all platforms. None of this should be
        necessary with Apache 1.2 and later.</p>
        <hr />
      </li>

      <li>
        <a id="stopping" name="stopping"><strong>I upgraded from an
        Apache version earlier than 1.2.0 and suddenly I have
        problems with Apache dying randomly or not restarting
        properly</strong></a> 

        <p>You should read <a href="#redhat">the previous note</a>
        about problems with RedHat installations. It is entirely
        likely that your installation has start/stop/restart
        scripts which were built for an earlier version of Apache.
        Versions earlier than 1.2.0 had various race conditions
        that made it necessary to use <code>kill -9</code> at times
        to take out all the httpd servers. But that should not be
        necessary any longer. You should follow the <a
        href="../stopping.html">directions on how to stop and
        restart Apache</a>.</p>

        <p>As of Apache 1.3 there is a script
        <code>src/support/apachectl</code> which, after a bit of
        customization, is suitable for starting, stopping, and
        restarting your server.</p>
        <hr />
      </li>

      <li>
        <a id="setservername" name="setservername"><b>When I try to
        start Apache from a DOS window, I get a message like
        "<samp>Cannot determine host name. Use ServerName directive
        to set it manually.</samp>" What does this mean?</b></a> 

        <p>It means what it says; the Apache software can't
        determine the hostname of your system. Edit your
        <samp>conf\httpd.conf</samp> file, look for the string
        "ServerName", and make sure there's an uncommented
        directive such as</p>

        <dl>
          <dd><code>ServerName localhost</code></dd>
        </dl>

        <p>or</p>

        <dl>
          <dd><code>ServerName www.foo.com</code></dd>
        </dl>

        <p>in the file. Correct it if there one there with wrong
        information, or add one if you don't already have one.</p>

        <p>Also, make sure that your Windows system has DNS
        enabled. See the TCP/IP setup component of the Networking
        or Internet Options control panel.</p>

        <p>After verifying that DNS is enabled and that you have a
        valid hostname in your <samp>ServerName</samp> directive,
        try to start the server again.</p>
        <hr />
      </li>

      <li>
        <a id="ws2_32dll" name="ws2_32dll"><b>When I try to start
        Apache for Windows, I get a message like "<samp>Unable To
        Locate WS2_32.DLL...</samp>". What should I do?</b></a> 

        <p>Short answer: You need to install Winsock 2, available
        from <a
        href="http://www.microsoft.com/windows95/downloads/">http://www.microsoft.com/windows95/downloads/</a></p>

        <p>Detailed answer: Prior to version 1.3.9, Apache for
        Windows used Winsock 1.1. Beginning with version 1.3.9,
        Apache began using Winsock 2 features (specifically,
        WSADuplicateSocket()). WS2_32.DLL implements the Winsock 2
        API. Winsock 2 ships with Windows NT 4.0 and Windows 98.
        Some of the earlier releases of Windows 95 did not include
        Winsock 2.</p>
        <hr />
      </li>

      <li>
        <a id="WSADuplicateSocket"
        name="WSADuplicateSocket"><b>Apache for Windows does not
        start. Error log contains this message: "<samp>[crit]
        (10045) The attempted operation is not supported for the
        type of object referenced: Parent: WSADuplicateSocket
        failed for socket ###</samp>". What does this mean?</b></a>
        

        <p>We have seen this problem when Apache is run on systems
        along with Virtual Private Networking clients like Aventail
        Connect. Aventail Connect is a Layered Service Provider
        (LSP) that inserts itself, as a "shim," between the Winsock
        2 API and Window's native Winsock 2 implementation. The
        Aventail Connect shim does not implement
        WSADuplicateSocket, which is the cause of the failure.</p>

        <p>The shim is not unloaded when Aventail Connect is shut
        down. Once observed, the problem persists until the shim is
        either explicitly unloaded or the machine is rebooted.
        Another potential solution (not tested) is to add
        <code>apache.exe</code> to the Aventail "Connect Exclusion
        List".</p>

        <p>Apache is affected in a similar way by <em>any</em>
        firewall program that isn't correctly configured. Assure
        you exclude your Apache server ports (usually port 80) from
        the list of ports to block. Refer to your firewall
        program's documentation for the how-to.</p>
        <hr />
      </li>

      <li>
        <a id="err1067" name="err1067"><b>When I try to start
        Apache on Windows, I get a message like "<code>System error
        1067 has occurred. The process terminated
        unexpectedly</code>." What does this mean?</b></a> 

        <p>This message means that the Web server was unable to
        start correctly for one reason or another. To find out why,
        execute the following commands in a DOS window:</p>
<pre>
    c:
    cd "\Program Files\Apache Group\Apache"
    apache
 
</pre>

        <p>(If you don't get the prompt back, hit Control-C to
        cause Apache to exit.)</p>

        <p>The error you see will probably be one of those
        preceding this question in the FAQ.</p>

        <p>As of Apache 1.3.14, first check the Windows NT Event
        Log for Application errors using the Windows NT/2000 Event
        Viewer program. Any errors that occur prior to opening the
        Apache error log will be stored here, if Apache is run as a
        Service on NT or 2000. As with any error, also check your
        Apache error log.</p>
        <hr />
      </li>

      <li><a id="suseFDN" name="suseFDN"><b>On a SuSE Linux system, I try and 
          configure access control using basic authentication.
	  Although I follow the example exactly, authentication
	  fails, and an error message "<code>admin: not a valid
	  FDN: ....</code>" is logged.</b></a>

          <p>
	  In the SuSE distribution, additional 3rd party authentication
	  modules have been added and activated by default. These modules
	  interfere with the Apache standard modules and cause Basic
	  authentication to fail. Our recommendation is to comment all
	  those modules in <code>/etc/httpd/suse_addmodule.conf</code>
	  and <code>/etc/httpd/suse_loadmodule.conf</code> which are not
	  actually required for running your server.
          </p><hr />
      </li>

     <li><a id="codered" name="codered"><b>Why do I have weird entries in my
          logs asking for <code>default.ida</code> and
          <code>cmd.exe</code>?</b></a>
      
          <p>The host requesting pages from your website and creating
          those entries is a Windows machine running IIS that has been
          infected by an Internet worm such as Nimda or Code Red. You
          can safely ignore these error messages as they do not affect
          Apache.  ApacheWeek has an <a
          href="http://www.apacheweek.com/features/codered">article</a>
          with more information.</p><hr />
     </li>

    <li><a id="restart" name="restart"><b>Why am I getting server restart
    messages periodically, when I did not restart the server?</b></a>

          <p>Problem: You are noticing restart messages in your error log,
          periodically, when you know you did not restart the server
          yourself:</p>

<pre>
[Thu Jun  6 04:02:01 2002] [notice] SIGHUP received.  Attempting to restart
[Thu Jun  6 04:02:02 2002] [notice] Apache configured -- resuming normal operations
</pre>

          <p>Check your cron jobs to see when/if your server logs are being
          rotated. Compare the time of rotation to the error message time.
          If they are the same, you can somewhat safely assume that the 
          restart is due to your server logs being rotated.</p><hr />
     </li>

     <li><a id="modulemagic" name="modulemagic"><b>Why am I getting
          &quot;module <em>module-name</em> is not compatible with this version
          of Apache&quot; messages in my error log?</b></a>
      
          <p>Module Magic Number (MMN) is a constant defined in Apache
          source that is associated with binary compatibility of
          modules. It is changed when internal Apache structures,
          function calls and other significant parts of API change in
          such a way that binary compatibility cannot be guaranteed any
          more. On MMN change, all third party modules have to be at
          least recompiled, sometimes even slightly changed in order
          to work with the new version of Apache.</p>

          <p>If you're getting the above error messages, contact the
          vendor of the module for the new binary, or compile it if
          you have access to the source code.</p><hr />
     </li>

    </ol>
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